This invention relates to data storage systems in general, and more specifically to an inventory control apparatus and method for use in a data storage system.
Many different types of data storage systems or libraries exist and are being used to store data cartridges at known locations and to retrieve those data cartridges from the storage locations so that data may be written to or read from those data cartridges. Such data storage systems are typically used to store magnetic data cartridges for long term archival purposes or for short term back-up system purposes. However, other types of data storage devices comprising virtually any type of data storage medium could also be stored within the data storage systems.
A typical data storage system may include one or more different types of cartridge receiving devices for holding the various data cartridges. For example, one type of cartridge receiving device may comprise a cartridge storage rack or xe2x80x9cmagazine.xe2x80x9d The cartridge storage racks or magazines usually include cartridge storage slots which serve as storage locations for the data cartridges. The various cartridge storage racks or magazines of the data storage system may be positioned within magazine drawers which are commonly arranged so that they form one or more horizontal stacks. Alternatively, the magazine drawers may be arranged so that they form one or more vertical stacks. Another type of cartridge receiving device may comprise a cartridge read/write device. The cartridge read/write device may be located adjacent a cartridge magazine, although the cartridge read/write device may be positioned at any convenient location.
The data storage system may also be provided with a cartridge handling system for transporting the data cartridges between the various cartridge receiving devices, e.g., between the cartridge storage racks and the cartridge read/write devices. A typical cartridge handling system may include a cartridge access device for accessing the various data cartridges contained in the cartridge receiving devices, as well as a positioning system for moving the cartridge access device among the various cartridge receiving devices contained in the data storage system.
Since the contents of the data storage systems and/or the arrangement of the data cartridges therein may be periodically changed, most data storage systems are provided with an inventory system. The inventory system may be used for keeping track of the presence, locations and identities of the various data cartridges within the data storage system. Typically, the inventory system is internal to the data storage system, although such need not be the case.
The inventory system may include a bar code reading device or other device for identifying data cartridges. More specifically, each of the various data cartridges stored within the data storage system may be provided with a bar code label having data encoded thereon that identifies the data cartridge on which it is placed. The bar code reading device may be used to read the data on the bar code labels to keep track (i.e., inventory) of the presence, locations and identities of the various data cartridges within the data storage system. For example, the bar code reading device may be moved among the various cartridge receiving devices and read the bar codes on the cartridges within those cartridge receiving devices so that their identities and respective locations may be obtained. This information may then be compiled or stored in an xe2x80x9cinventory listxe2x80x9d which the data storage system may later access to locate a particular data cartridge.
Data storage systems of the type described above are usually connected to a host computer system which may access or store data on the data cartridges. For example, if certain data contained on a particular data cartridge is desired, the host computer system will issue commands to a control system associated with the data storage system. In response to those commands, the control system will actuate the positioning system which moves the cartridge access device along the cartridge storage racks or magazines until the cartridge access device is positioned adjacent to where the desired data cartridge should be located according to the inventory list. The bar code reading device may assist the control system in determining when the cartridge access device has been positioned adjacent the desired data cartridge. In other words, the bar code reading device reads the bar code label positioned on the data cartridge to verify whether the data cartridge is the desired data cartridge. If not, the cartridge access device may be moved to another data cartridge. After the desired data cartridge has been located, the cartridge access device may then remove the desired cartridge from the cartridge storage rack and carry it to the cartridge read/write device. Once properly positioned adjacent the cartridge read/write device, the cartridge access device may insert the selected data cartridge into the cartridge read/write device so that the host computer may thereafter read data from or write data to the selected data cartridge. After the read/write operation is complete, the cartridge access device may remove the data cartridge from the cartridge read/write device and return it to its appropriate location in the cartridge storage rack.
It is often necessary or desirable for a system operator to periodically access one or more of the data cartridges contained within such a data storage system. For example, it may be necessary for the system operator to remove certain of the data cartridges from time to time if they become filled with data that is to be archived at another location. The system operator may then replace the filled data cartridges with blank or empty data cartridges. In another situation, the system operator may desire to remove one or more of the data cartridges and replace it or them with a substitute data cartridge or cartridges containing different data.
In order to accommodate the foregoing needs, many data storage systems are provided with extendable drawers that can be manually pulled open by the system operator to allow the system operator to access the data cartridges stored in the data storage systems. Such extendable drawers are typically locked in their closed positions only when the data storage system is operational. That is, the drawers may be opened by the system operator if the data storage system is shut down whether intentionally or unintentionally (e.g., a power failure). Since the system operator could have exchanged, removed, or added a data cartridge within a drawer while the data storage system was shut down, the data storage system must inventory each drawer when rebooted.
Considering the large number of data cartridges that may be stored within a data storage system, the time needed for the inventory can be quite substantial. Such a time-consuming process is difficult to justify, especially if the data cartridges within the data storage system were not changed.
The time-consuming inventories can be especially troublesome for system operators and support engineers who often must service the data storage system (e.g., for a firmware upgrade) according to stringent time deadlines. Typically, the data storage system must be shut down before any changes (e.g., circuit board replacement) can be made thereto. Thus, even though the system operator may be under stringent deadlines, the astute system operator will need to set aside sufficient time to allow the data storage system to reboot and inventory its data cartridges. In actuality, however, the system operator normally reboots the data storage system more than once and will lose a considerable amount of time while waiting for the inventory process to be completed.
Accordingly, a need remains for a data storage system that allows a system operator to reboot the data storage system without an inventory. Ideally, the system operator should be able to select whether the data storage system will perform an inventory when rebooted, and select which data cartridge storage locations, if any, will be inventoried.
Inventory control apparatus for a data storage system may comprise a first setting and a second setting. The first setting causes the data storage system to inventory a data cartridge storage location of the data storage system after the data storage system has undergone a power cycle. The second setting causes the data storage system to not perform an inventory after the data storage system has undergone the power cycle.
Also disclosed is an inventory control method for use in a data storage system that comprises the steps of: providing inventory control apparatus operatively associated with the data storage system, the inventory control apparatus being operable in a first setting and a second setting, the first setting causing the data storage system to inventory a data cartridge storage location of the data storage system after the data storage system has undergone a power cycle, the second setting causing the data storage system to not perform an inventory after the data storage system has undergone the power cycle; selecting the first setting so that said data storage system inventories the data cartridge storage location after said data storage system has undergone the power cycle, or, in the alternative; selecting the second setting so that said data storage system does not perform an inventory after said data storage system has undergone the power cycle.